mAh vs. Wh — What's the Difference?

mAh stands for milliampere-hour, quantifying the total amount of energy a battery can deliver in one hour at a consistent rate of discharge. Wh, or watt-hour, represents the battery's energy capacity, correlating to the power it can provide over a specific period. While mAh is centered around the electric charge, Wh integrates both the voltage and the time factor, offering a comprehensive view of the battery's potential.

The concept of mAh is widely used in describing the capacity of smaller batteries, like those in smartphones, emphasizing the duration a battery can last under a nominal load. Conversely, Wh is a broader measure, often applied to larger systems or devices, encapsulating the total energy output without being confined to a fixed voltage, thus providing a more universal comparison of battery capacities across different technologies.

To calculate Wh from mAh, one must consider the voltage of the battery, highlighting the interconnectedness of these units. While mAh alone might indicate a battery's longevity, it doesn't account for the device's power demands. Wh, on the other hand, incorporates both the voltage and the time, painting a fuller picture of the battery's capability to power a device.

In practical terms, a higher mAh value suggests a longer battery life for a device, assuming a constant power draw. However, Wh extends this understanding by illustrating how much work the battery can actually perform, which is vital in assessing batteries for more power-intensive or longer-duration applications.

Understanding the distinction between mAh and Wh is crucial for consumers. mAh offers a quick snapshot of battery capacity, particularly useful for low-power, portable devices. In contrast, Wh provides a more detailed and comprehensive understanding of a battery's energy content, crucial for higher-powered devices and when considering energy efficiency and operational duration.